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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4866) NameNode error in commitBlockSynchronization
Date Thu, 18 Dec 2008 22:37:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12657932#action_12657932
] 

Tsz Wo (Nicholas), SZE commented on HADOOP-4866:
------------------------------------------------

> Oddly enough, these clients seem to have survived cluster reboots, namenode restarts,
...

One of our HDFS design is to let client survives namenode restart.  And you just have shown
that it works.  :)

> However, I'd claim that if the file fails, there shouldn't be any way repeated reads
should cause problems.
>
> That is, if read is called on DFSClient repeatedly even after errors, it shouldn't cause
any issues on the DN side.

I agree that we should protect our servers against denied of service attack.  However, we
are not in that stage yet.

Do you think the current patch is good?

> NameNode error in commitBlockSynchronization
> --------------------------------------------
>
>                 Key: HADOOP-4866
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4866
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.19.0
>            Reporter: Brian Bockelman
>         Attachments: 4866_20081215.patch, 4866_20081216.patch, 4866_20081217.patch
>
>
> The NameNode continuously has an error in the commitBlockSynchronization.  This happens
for ~5 blocks at a rate of 5-10Hz.  I have no idea when this started happening because this
has been going on for days, well past the start of our current logs.
> This appears to be a new symptom in 0.19.0, but I have no idea what could be causing
it.

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